Looking for Bendix G-15 computer

[Jon Elson]

Hello,

Anyone know where a Bendix G-15 computer may be
laying? This is a late-1950's vacuum tube (valve
in British) computer with drum memory. It was
housed in a refrigerator-sized blue cabinet with
doors that opened on the side for service.
It had 3 DeArsonval meters on the front, and none
of the usual lights and switches of older computer
consoles. All "console" functions were done on an
ancient IBM typewriter. A friend of a friend is
looking for one to refurbish. (Oh, yes, he's
crazy, SERIOUSLY demented, to want to repair one
of these beasts!) We had one at Washington
University about 1970, picked it up for shipping
cost from NASA. After much fooling around, I
determined the drum was deeply gouged on a couple
of tracks. I don't know what became of it after
that. But, nobody seems to know where it went.
There were 300 or more of these made, and were a
favorite of highway departments for cut and fill
highway earthmoving.

Here's a link with a pic
http://www.computermuseum.li/Testpage/Bendix-G15-1950s.htm

The demented guy would really love to hear that
somebody has one saved in a basement or back room,
somewhere.

Jon

 

[Robert Baer]

Jon Elson wrote:

Hello,

Anyone know where a Bendix G-15 computer may be laying? This is a
late-1950's vacuum tube (valve in British) computer with drum memory.
It was housed in a refrigerator-sized blue cabinet with doors that
opened on the side for service.
It had 3 DeArsonval meters on the front, and none of the usual lights
and switches of older computer consoles. All "console" functions were
done on an ancient IBM typewriter. A friend of a friend is looking for
one to refurbish. (Oh, yes, he's crazy, SERIOUSLY demented, to want to
repair one of these beasts!) We had one at Washington University about
1970, picked it up for shipping cost from NASA. After much fooling
around, I determined the drum was deeply gouged on a couple of tracks.
I don't know what became of it after that. But, nobody seems to know
where it went. There were 300 or more of these made, and were a favorite
of highway departments for cut and fill highway earthmoving.

Here's a link with a pic
http://www.computermuseum.li/Testpage/Bendix-G15-1950s.htm

The demented guy would really love to hear that somebody has one saved
in a basement or back room, somewhere.

Jon
Learned programming on one at UC Berzerkley, basement of Cory Hall as

i remember.
Try a query to one of the older instructors in the computing department?

 

[Jon Elson]

Robert Baer wrote:

Learned programming on one at UC Berzerkley, basement of Cory Hall as
i remember.
Try a query to one of the older instructors in the computing department?

The people who actually used these are mostly retired or passed away.
The only ones who remember them are mostly people who got to play with
them after the machines were "semi-retired". I'd guess the G-15 went
into a very rapid retirement when core memory and discrete transistors
came out in the very early 1960's. A PDP-5 could mostly run rings
around a G-15. When programmed to the umpteenth, with the instructions
optimally scattered around the drum, you could get about 3000
instructions/second out of a G-15. A PDP-5 was a 12-bit parallel
machine, and could do at least 50,000 IPS. The memory worked out to
about twice the size of the G-15's. I don't know about the reliability
of the G-15, but a PDP-5 was a very reliable system, the only thing I
remember ever having to fix was worn-out console switches.

Jon

 

[krw]

On Sun, 25 Jan 2009 21:03:04 -0600, Jon Elson <elson@pico-systems.com>
wrote:

Hello,

Anyone know where a Bendix G-15 computer may be
laying? This is a late-1950's vacuum tube (valve
in British) computer with drum memory. It was
housed in a refrigerator-sized blue cabinet with
doors that opened on the side for service.
It had 3 DeArsonval meters on the front, and none
of the usual lights and switches of older computer
consoles. All "console" functions were done on an
ancient IBM typewriter. A friend of a friend is
looking for one to refurbish. (Oh, yes, he's
crazy, SERIOUSLY demented, to want to repair one
of these beasts!) We had one at Washington
University about 1970, picked it up for shipping
cost from NASA. After much fooling around, I
determined the drum was deeply gouged on a couple
of tracks. I don't know what became of it after
that. But, nobody seems to know where it went.
There were 300 or more of these made, and were a
favorite of highway departments for cut and fill
highway earthmoving.

Gees, our EE department had G20s (the semiconductor version) that they
got for $.01/lb., including shipping, about that time. They had
three, though one didn't leave the crates intact (raised floor queen).

Here's a link with a pic
http://www.computermuseum.li/Testpage/Bendix-G15-1950s.htm

The demented guy would really love to hear that
somebody has one saved in a basement or back room,
somewhere.

 

[Robert Baer]

Jon Elson wrote:

Robert Baer wrote:

Learned programming on one at UC Berzerkley, basement of Cory Hall
as i remember.
Try a query to one of the older instructors in the computing
department?


The people who actually used these are mostly retired or passed away.
The only ones who remember them are mostly people who got to play with
them after the machines were "semi-retired". I'd guess the G-15 went
into a very rapid retirement when core memory and discrete transistors
came out in the very early 1960's. A PDP-5 could mostly run rings
around a G-15. When programmed to the umpteenth, with the instructions
optimally scattered around the drum, you could get about 3000
instructions/second out of a G-15. A PDP-5 was a 12-bit parallel
machine, and could do at least 50,000 IPS. The memory worked out to
about twice the size of the G-15's. I don't know about the reliability
of the G-15, but a PDP-5 was a very reliable system, the only thing I
remember ever having to fix was worn-out console switches.

Jon
As i vaguely remember, there was a small "scratchpad" core memory

which i think was used as a lookup for multiply (??).
Darn good for learning especially for organizing a program (read:
optimizing).

 

[krw]

In article <T_OdneEUWavKPuPUnZ2dnUVZ_uSdnZ2d@posted.localnet>,
robertbaer@localnet.com says...>

Jon Elson wrote:
Robert Baer wrote:

Learned programming on one at UC Berzerkley, basement of Cory Hall
as i remember.
Try a query to one of the older instructors in the computing
department?


The people who actually used these are mostly retired or passed away.
The only ones who remember them are mostly people who got to play with
them after the machines were "semi-retired". I'd guess the G-15 went
into a very rapid retirement when core memory and discrete transistors
came out in the very early 1960's. A PDP-5 could mostly run rings
around a G-15. When programmed to the umpteenth, with the instructions
optimally scattered around the drum, you could get about 3000
instructions/second out of a G-15. A PDP-5 was a 12-bit parallel
machine, and could do at least 50,000 IPS. The memory worked out to
about twice the size of the G-15's. I don't know about the reliability
of the G-15, but a PDP-5 was a very reliable system, the only thing I
remember ever having to fix was worn-out console switches.

Jon
As i vaguely remember, there was a small "scratchpad" core memory
which i think was used as a lookup for multiply (??).
Darn good for learning especially for organizing a program (read:
optimizing).

According to the wiki, multiply (Divide, and square root) was done
in a built-in subroutine. The IBM 1620, A.K.A. the CADET (Can't
Add, Didn't Even Try), used lookup tables for ADD.

Interesting stuff at:
http://en.wikipedia.org/wiki/Bendix_G-15

 

[Jon Elson]

Robert Baer wrote:

As i vaguely remember, there was a small "scratchpad" core memory
which i think was used as a lookup for multiply (??).
Darn good for learning especially for organizing a program (read:
optimizing).
No, the machine was designed entirely too early

for core. I am fairly familiar with it, I tried
to help resurrect one about 1971. Jay W Forrester
(with the help of my freshman adviser William
Papian) got the first coincident current core
memory working in 1951. It took a few years for
industry to gear up to produce commercial core
stacks. The G-15 was adapted from the Turing ACE.
Although the G-15 was brought out in 1956, the
design of the machine started much earlier. I
wouldn't be too surprised if somebody adapted a
core stack to the machine for some purpose, but
the basic cycle time of the machine was SOOOO
slow, that it would not have helped much on speed.
It certainly would have helped expand the
critically tiny memory on the G-15, though. The
G-15 was a serial-arithmetic machine, and
optimally executed 3000 instructions/second. But,
it was a rare program that could come close to
that performance. Worst-case was a program
totally un-optimized for next instruction
location, it would run at 50 IPS (the delay of the
long tracks on the drum).

Jon